The history of the universe — from the Big Bang to the end of the year — day by day

Plagues and Peoples

Every day on Logarithmic History we cover an interval 5.46% shorter than the preceding day. From covering the first 754 million years after the Big Bang on January 1, we’re down to just one century worth of history today.

And it’s a bad century for both Rome and China. Rome goes through an economic crisis, with a huge currency devaluation. Political life goes to hell too. From 235-284 there are 20 Emperors; 18 of them die violently. The Roman Empire experiences multiple, destructive invasions by barbarians. It recovers toward the end of the century, but in a heavily militarized and authoritarian form. And in China the Han dynasty disappears entirely after 220, to be replaced by three kingdoms of barbarian origin.

This coincidence of catastrophes may be more than just bad luck. Put it this way: If we look at the Big Picture, going way back on our calendar, and turning for a moment from human history to the evolution of life, we can summarize biological evolution since the Cambrian as:

Now and then, a physical catastrophe punctuates the history of life, causing mass extinctions, from which living things slowly recover.

Returning to human history, we can summarize social evolution since the adoption of agriculture as:

A process of escalation, in which conflicts between rival groups (kin groups, empires) are drivers of increasing social complexity …

but…

Now and then, a biological catastrophe – in the form of an epidemic of some new disease – punctuates human history, causing major population losses, and often political and social collapse as well.

One such catastrophe led to the collapse of New World societies in the face of Old World diseases after 1492. But the Old World too must have had its own earlier catastrophes as the great killer diseases – the diseases of civilization that need a minimum population to keep going – established themselves.

Epidemic disease may have made a major contribution to the fall of Rome and of Han China. Rome suffered two massive epidemics, one from 165-180, another from 251-266. It’s plausible (and someday geneticsts will tell us whether it’s true or not) that these epidemics represent the arrival of smallpox and measles in the West. And there may be a similar story to tell about China, also stricken by epidemics at this time. The opening of the Silk Road and of trade across the Indian Ocean allowed precious goods and new ideas to travel between civilizations. It also opened the way for lethal microorganisms. (The classic book here is William McNeill’s Plagues and Peoples.)